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41.
W. James Gauderman 《Statistics and Computing》1995,5(3):237-243
The field of genetic epidemiology is growing rapidly with the realization that many important diseases are influenced by both genetic and environmental factors. For this reason, pedigree data are becoming increasingly valuable as a means of studying patterns of disease occurrence. Analysis of pedigree data is complicated by the lack of independence among family members and by the non-random sampling schemes used to ascertain families. An additional complicating factor is the variability in age at disease onset from one person to another. In developing statistical methods for analysing pedigree data, analytic results are often intractable, making simulation studies imperative for assessing the performance of proposed methods and estimators. In this paper, an algorithm is presented for simulating disease data in pedigrees, incorporating variable age at onset and genetic and environmental effects. Computational formulas are developed in the context of a proportional hazards model and assuming single ascertainment of families, but the methods can be easily generalized to alternative models. The algorithm is computationally efficient, making multi-dataset simulation studies feasible. Numerical examples are provided to demonstrate the methods. 相似文献
42.
Recently, there has been a lot of interest in group technology (GT) from researchers as well as from practitioners. This interest is explained by the fact that GT supports new manufacturing philosophies. One of the main issues in GT is the part family formation problem which is concerned with grouping similar products into same families. Many researchers have tackled this problem and many algorithms have been proposed for it. In this paper, we present a genetic technique-based heuristic for the quadratic integer programming model of the part family formation problem which was formulated by Kusiak et al. (1986). The heuristic is tested on several problems from the literature, and preliminary results are very promising. 相似文献
43.
Many optimization problems from the industrial engineering world, in particular the manufacturing systems, are very complex in nature and quite hard to solve by conventional optimization techniques. There has been increasing interest in imitating living beings to solve such kinds of hard optimization problems. Simulating the natural evolutionary process of human beings results in stochastic optimization tech niques called evolutionary algorithms, which can often outperform conventional optimization methods when applied to difficult real-world problems. There are currently three main avenues of this research: genetic algorithms (GAs), evolutionary programming (EP) and evolution strategies (ESs). Among them, genetic algorithms are perhaps the most widely known types of evolutionary algorithms today. During the past years, several GAs for the job-shop scheduling problems have been proposed, each with different chromosome representation. In this paper, the different GAs are collected from the literature and an attempt has been made to evaluate them. The benchmark problems available in open literature are used for evaluation and the performance measure considered is makespan. The algorithms are coded in C+ +. 相似文献
44.
45.
陶江 《华北水利水电学院学报(社会科学版)》2007,23(2):72-77
经济学与自然科学的元素结构具有惊人的相似性。运用结构主义方法,可以改进经济学的基因结构。与生物DNA的基本片段相比较,《资本论》的基因片段尚未健全。由于历史限制,马克思尚未建立起多维对称的基因结构。但《资本论》的基因片段可以自我复制、自我完善。《资本论》基因片段的自我完善,对于建立经济学元素周期率和经济学DNA结构,对于21世纪经济学的变革意义重大。 相似文献
46.
不确定条件下新产品供应链零部件供应商选择的优化研究 总被引:1,自引:0,他引:1
本文运用可信性理论建立了模糊需求条件下新产品供应链配置的模糊机会约束规划模型,对模型的求解进行了分析,并用遗传算法进行求解。算例分析表明,运用本文提出的方法可以从供应商的选择、阶段库存和客户服务水平三个方面对模糊需求条件下的新产品供应链进行配置优化。 相似文献
47.
从一汽轿车股份有限公司仓储中心WMS的实际业务出发,考虑物料的进出库频率和货架的受力情况,为货位分配问题建立多目标优化模型.利用遗传算法中的并列选择法,设计遗传算子并进行求解.优化后结果表明:可以减少堆垛机的运行距离,合理安排货物的分配,减少人工作业,提高仓储的利用效率,降低企业成本. 相似文献
48.
Many areas of statistical modeling are plagued by the “curse of dimensionality,” in which there are more variables than observations. This is especially true when developing functional regression models where the independent dataset is some type of spectral decomposition, such as data from near-infrared spectroscopy. While we could develop a very complex model by simply taking enough samples (such that n > p), this could prove impossible or prohibitively expensive. In addition, a regression model developed like this could turn out to be highly inefficient, as spectral data usually exhibit high multicollinearity. In this article, we propose a two-part algorithm for selecting an effective and efficient functional regression model. Our algorithm begins by evaluating a subset of discrete wavelet transformations, allowing for variation in both wavelet and filter number. Next, we perform an intermediate processing step to remove variables with low correlation to the response data. Finally, we use the genetic algorithm to perform a stochastic search through the subset regression model space, driven by an information-theoretic objective function. We allow our algorithm to develop the regression model for each response variable independently, so as to optimally model each variable. We demonstrate our method on the familiar biscuit dough dataset, which has been used in a similar context by several researchers. Our results demonstrate both the flexibility and the power of our algorithm. For each response variable, a different subset model is selected, and different wavelet transformations are used. The models developed by our algorithm show an improvement, as measured by lower mean error, over results in the published literature. 相似文献
49.
根据资料总体分布特征,推导出DNA 指纹与两种类型性状间的相关度量公式。论述了使用该公式筛选标记性状指纹的合理性,同时给出了相应的计算和统计分析方法 相似文献
50.
A two-sided assembly line balancing problem is typically found in plants producing large-sized high-volume products, e.g. buses and trucks. The features specific to the assembly line are described in this paper, which are associated with those of: (i) two-sided assembly lines; (ii) positional constraints; and (iii) balancing at the operational time. There exists a large amount of literature in the area of line balancing, whereby it has mostly dealt with one-sided assembly lines. A new genetic algorithm is developed to solve the problem, and its applicability and extensibility are discussed. A genetic encoding and decoding scheme, and genetic operators suitable for the problem are devised. This is particularly emphasized using problem-specific information to enhance the performance of the genetic algorithm (GA). The proposed GA has a strength that it is flexible in solving various types of assembly line balancing problems. An experiment is carried out to verify the performance of the GA, and the results are reported. 相似文献